In many mirror products today a very uniform fit between the edge of the glass shape and the surrounding flush mounted bezel or housing is desired to produce an aesthetically pleasing product. A large or non-uniform gap between the glass edge and the bezel or housing is unsightly. A uniform gap produces a smooth, pleasing seamless transition between the bezel or housing and the mirror element. In a traditional scribe and break process the score or scribe line of the desired glass shape can be placed very accurately but the subsequent breaking process produces an uneven glass edge. The glass “grows” in size because the uneven edge has peaks and valleys in close proximity and the peaks add to the overall size of the glass shape. The appearance of the shiny, non-uniform glass edge is undesirable because of its non-uniform reflection of light. A smooth, frosty edge appearance can be obtained by additional post seaming or grinding the glass. Enough glass must be removed to frost or smooth all of the deep valleys created during the glass separation process. This results in the glass shape being undersized relative to the scribed shape. Because of tool wear and inconsistent removal rate of glass over time, the size of the final glass shape changes with time. As a result a tight consistent glass fit to a bezel or housing is difficult to maintain. Glass can also be cut using a high pressure water jet process. In this process a high pressure jet of water loaded with abrasive particles traverses along a path and erodes away the glass as it travels. The final glass shape and size is dependent on many variables: The diameter of the jet, the water pressure, the size and distribution of abrasive particles, jet traverse speed. Maintaining a consistent accurate shape over time is difficult. The high pressure impingement can also chip and damage the glass edge. More material is removed from the water jet entrance side of the glass than the exit side of the glass resulting in an edge with a tapered erosion pattern. This also negatively impacts shape cut accuracy and edge appearance. Grinding, seaming and water jet shaping of glass abrades the glass away by removing chips or particles of glass. As a result the finished glass piece has chips or particles of glass that are loosely attached and can be dislodged is subsequent handling operations. This is undesirable if subsequent processing operations are sensitive to particulate contamination.
As mentioned above, it is often aesthetically desirable to have a frosty or smooth shiny/polished glass edge. A frosty edge can be achieved by grinding or seaming the glass edge, acid etching the glass edge or coating the glass edge with a paint or coating that produces a frosty appearance. A grinding or seaming process produces a frosty edge by roughening the glass surface through a process of mechanically “fracturing” small particles off of the glass surface using a harder than glass abrasive media. The glass cracking and fracturing damage penetrates a substantial depth into the glass creating a less than ideal surface full of defects. These defects create weak spots in the glass that can cause the glass to break when stresses thermally or mechanically. Acid etch frosting requires exposing the glass to a corrosive material that presents safety hazards when handled in bulk in a production environment. Painting the glass edge requires additional coating and curing processing steps.